This invention is directed to reagent packages having valve controlled openings and more particularly to a novel valve sealing system for a reagent package.
Reagent packages such as shown in U.S. Pat. Nos. 6,043,097 and 6,511,634 include at least one chamber that can hold two ingredients intended for later mixing within the reagent package, separate from each other, until the mixing of such ingredients is desired. For example, as disclosed in U.S. Pat. No. 6,043,097, a reagent package holds a reagent in powder form and also contains, in a sealed glass ampoule, a selected amount of reconstituting liquid ingredient for the powder reagent.
It should be noted that the reagent packages shown in U.S. Pat. Nos. 6,043,097 and 6,511,634 are dual packages formed as an integral unit. Each package is similar in structure and function and has a separate packaging section arranged side by side. The packaging sections are non-communicable.
Since each packaging section is similar in structure and function, only one of the packaging sections will be described herein and the term reagent package will be used synonymously with the term packaging section unless otherwise indicated.
When it is desired to reconstitute the powder reagent into a liquid reagent the glass ampoule with the reconstituting liquid is crushed within the reagent package. The reconstituting liquid, although liberated from the broken ampoule, remains confined within the reagent package where it can intermix within the reagent package with the dry powder reagent. The dry powder reagent is thus reconstituted in liquid form within the reagent package. The reagent package can then serve as a reservoir to supply the reconstituted liquid reagent to a known sample analysis system.
The reagent package previously referred to includes an opening in a lid of the package through which a liquid reagent is aspirated from the chamber of the reagent package. The opening in the lid is also referred to as the chamber opening or package opening. The reagent package also includes a filter in the chamber that prevents broken glass from being aspirated with the liquid reagent.
In the previously cited patents the opening of the reagent package is closable by a rocker valve. The rocker valve is pivotable from a valve closed position, that provides a substantially leak tight seal of the package opening, to a valve open position wherein the package opening is accessible by an aspiration device. Aspiration of reagent from the reagent package is usually made in amounts needed to provide desired reactions with other agents in a known sample analysis system. For example, an aspiration of 4 microliters of reagent is feasible for sustaining a reaction that will yield or lead to definitive data in analyzing the blood chemistry of an individual.
The chamber of a known reagent package of the type previously referred to can be provided with approximately 20 to 22 ml of reagent. This amount of reagent is sufficient to supply a predetermined aspiration quantity that permits at least 1,250 separate aspirations of reagent.
Because the reagent in a reagent package is known to be extremely costly, it is desirable to minimize evaporation of reagent whenever possible, especially from the opening of the reagent chamber. It is also desirable to avoid the risk of reagent contamination that might occur if the opening to the reagent chamber were left in a continuously open condition. Therefore, the rocker valve of the reagent package is usually kept in a valve closed position before and after each aspiration of the reagent. The rocker valve is thus maintained in a valve open condition only for the duration of time needed to aspirate reagent. After a reagent aspiration cycle is completed the rocker valve is kept in a valve closed position until another reagent aspiration cycle is begun.
Thus the number of times the rocker valve on the reagent package is pivoted from a valve closed position to a valve open position corresponds to the number of aspiration cycles, such as for example, approximately 1,500 times, corresponding to approximately 1,500 cycles of reagent aspiration from the reagent package.
A known valve sealing arrangement between the rocker valve and the opening to the reagent chamber, when the rocker valve is in a valve closed position, includes an “O” ring valve seal that surrounds the chamber opening. Preferably the “O” ring is in a fixed position and the rocker valve pivots relative to the surface of the “O” ring. The rocker valve includes a valve face that confronts the opening to the chamber of the reagent package and remains in contact with the “O” ring when the rocker valve is in the valve closed position to provide a seal around the opening to the reagent chamber.
Known “O” rings in previous use are circular in cross section, where the sectional cutting plane is perpendicular to the plane of the “O” ring. A valve seal is produced when the “O” ring is compressed a predetermined amount by the valve face of the rocker valve. Generally the greater the compression of the “O” ring by the valve face, the more effective the seal becomes between the valve face and the “O” ring.
The “O” ring thus cooperates with the valve face of the rocker valve to provide a substantially leak tight seal between the rocker valve and the reagent chamber when the rocker valve is in the valve closed position.
Opening and closing of the rocker valve is preferably automated using an air cylinder with an actuating arm that engages the rocker valve with a predetermined force to pivot the valve from a valve closed position to a valve open position and vice versa. The force supplied by the actuating arm to the rocker valve must overcome the frictional force due to compression of the “O” ring by the valve face when the rocker valve is moved between the valve closed position and the valve open position.
It has been found desirable in a sample analysis system to limit the valve actuation force that is needed to open and close the rocker valve to an amount that is below 2 lbs. maximum. It is also desirable that the seal between the rocker valve and the “O” ring in a valve closed position should limit evaporation of reagent from the reagent package to a rate that is less than 0.05% per day. These system requirements have been difficult to attain with previously used “O” rings.
One problem is that in order to maintain a system evaporation rate of less than 0.05% of reagent per day the valve face compression of the “O” rings requires an actuation force in excess of 2 lbs to pivot the rocker valve from the valve closed position to the valve open position and vice-versa.
It is thus desirable to provide a valve sealing system for a reagent package that permits usage of a reagent valve actuation force of approximately 1.5 lbs. yet provides a seal between the rocker valve and the reagent package chamber that maintains a reagent evaporation rate of less than 0.05% per day.
Corresponding reference numbers indicate corresponding parts throughout the several views of the drawings.